Affiliation:
1. grid.258151.a 0000000107081323 State Key Laboratory of Food Science and Technology Jiangnan University 214122 Wuxi China
2. grid.258151.a 0000000107081323 Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi China
3. grid.258151.a 0000000107081323 Synergetic Innovation Center of Food Safety and Nutrition Jiangnan University Wuxi China
Abstract
Abstract
Previously we have characterized a threonine dehydratase mutant TDF383V (encoded by ilvA1) and an acetohydroxy acid synthase mutant AHASP176S, D426E, L575W (encoded by ilvBN1) in Corynebacterium glutamicum IWJ001, one of the best l-isoleucine producing strains. Here, we further characterized an aspartate kinase mutant AKA279T (encoded by lysC1) and a homoserine dehydrogenase mutant HDG378S (encoded by hom1) in IWJ001, and analyzed the consequences of all these mutant enzymes on amino acids production in the wild type background. In vitro enzyme tests confirmed that AKA279T is completely resistant to feed-back inhibition by l-threonine and l-lysine, and that HDG378S is partially resistant to l-threonine with the half maximal inhibitory concentration between 12 and 14 mM. In C. glutamicum ATCC13869, expressing lysC1 alone led to exclusive l-lysine accumulation, co-expressing hom1 and thrB1 with lysC1 shifted partial carbon flux from l-lysine (decreased by 50.1 %) to l-threonine (4.85 g/L) with minor l-isoleucine and no l-homoserine accumulation, further co-expressing ilvA1 completely depleted l-threonine and strongly shifted carbon flux from l-lysine (decreased by 83.0 %) to l-isoleucine (3.53 g/L). The results demonstrated the strongly feed-back resistant TDF383V might be the main driving force for l-isoleucine over-synthesis in this case, and the partially feed-back resistant HDG378S might prevent the accumulation of toxic intermediates. Information exploited from such mutation-bred production strain would be useful for metabolic engineering.
Funder
National Natural Science Foundation of China
National Key Basic Research Program of China
Fundamental Research Funds for the Central Universities
Publisher
Oxford University Press (OUP)
Subject
Applied Microbiology and Biotechnology,Biotechnology,Bioengineering
Cited by
28 articles.
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